Switch ImageStorageAccess over to GrTextureProxies

Split out of: https://skia-review.googlesource.com/c/10484/ (Omnibus: Push instantiation of GrTextures later (post TextureSampler))

Change-Id: I341de6ae121620d30e50bff21450878a18bdf4f2
Reviewed-on: https://skia-review.googlesource.com/16714
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
diff --git a/src/gpu/glsl/GrGLSLProgramBuilder.cpp b/src/gpu/glsl/GrGLSLProgramBuilder.cpp
index 5c3bee1..96b3359 100644
--- a/src/gpu/glsl/GrGLSLProgramBuilder.cpp
+++ b/src/gpu/glsl/GrGLSLProgramBuilder.cpp
@@ -358,7 +358,7 @@
     if (access.visibility() & kFragment_GrShaderFlag) {
         ++fNumFragmentImageStorages;
     }
-    GrSLType uniformType = access.texture()->texturePriv().imageStorageType();
+    GrSLType uniformType = access.proxy()->imageStorageType();
     return this->uniformHandler()->addImageStorage(access.visibility(), uniformType,
                                                    access.format(), access.memoryModel(),
                                                    access.restrict(), access.ioType(), name);